Pressure dependence of the band-gap energy in BiTeI

Abstract

The evolution of the electronic structure of BiTeI, a layered semiconductor with a van der Waals gap, under compression is studied by employing semilocal and dispersion-corrected density-functional calculations. Comparative analysis of the results of these calculations shows that the band-gap energy of BiTeI decreases till it attains a minimum value of zero at a critical pressure, after which it increases again. The critical pressure corresponding to the closure of the band gap is calculated, at which BiTeI becomes a topological insulator. Comparison of the critical pressure to the pressure at which BiTeI undergoes a structural phase transition indicates that the closure of the band gap would not be hindered by a structural transformation. Moreover, the band-gap pressure coefficients of BiTeI are computed, and an expression of the critical pressure is devised in terms of these coefficients. Our findings indicate that the semilocal and dispersion-corrected approaches are in conflict about the compressibility of BiTeI, which result in overestimation and underestimation, respectively. Nevertheless, the effect of pressure on the atomic structure of BiTeI is found to be manifested primarily as the reduction of the width of the van der Waals gap according to both approaches, which also yield consistent predictions concerning the interlayer metallic bonding in BiTeI under compression. It is consequently shown that the calculated band-gap energies follow qualitatively and quantitatively the same trend within the two approximations employed here, and the transition to the zero-gap state occurs at the same critical width of the van der Waals gap

Pressure-induced non-innocence in bis(1,2-dionedioximato)Pt(ii) complexes: an experimental and theoretical study of their insulator–metal transitions

“…5,7,8 This pressure-induced band inversion is reminiscent of the behaviour of some topological insulators. [25][26][27] According to the literature, the conductivity of Pt(dmg) 2 exhibits a similar behaviour to Pt(bqd) 2 under the application of pressure, however the insulator-to-metal transition occurs at much higher pressure (5 GPa). 5 To investigate the effect of pressure on the electronic structure of Pt(dmg) 2 we calculated the band structure, PDOS and -COHP PtÁ Á ÁPt interaction at 3.14 GPa (Fig.…”

Strongly Enhanced Berry Dipole at Topological Phase Transitions in BiTeI

“…Detailed ab initio studies of ∆ can be found in Ref. [35,36]. While the underestimation of the gap in semiconductors is a well-known feature of semilocal functionals, the fact that the description of the gap is better when the p 1/2 states are not included may be associated with a fortuitous cancelation of errors.…”

BiTeI Kristalinde Spin-Yörünge Yarılmasının Gerinim ile Değişimi

“…Hacim oranı ⁄ 0 değiştikçe hem bant aralık enerjisi hem de bantların şekli (dispersiyonu) değişim göstermektedir. Bant aralığı enerjisinin basınç ile gösterdiği değişim önceki bir yayınımızda [10]…”

“…Rashba tipi yarılmalar yarıiletken elektronlarının spin polarizasyonunun harici elektrik alanlarla kontrol edilmesine olanak sağladığı [2, 3] için BiTeI'nin spintronik cihazlarda kullanımı cazip görülmektedir. BiTeI basınç altında topolojik faz geçişi göstermesi [4][5][6][7][8][9][10] ve termoelektrik özellikleri [11][12][13] ile de dikkat toplamaktadır.…”